#colors() {
    primary: blue;
    secondary: green;
  }
  
  .button {
    color: #colors[primary];
    border: 1px solid #colors[secondary];
  }

// 混入别名
  #theme.dark.navbar {
    .colors(light) {
      primary: purple;
    }
    .colors(darks) {
      primary: black;
      secondary: red;
    }
  }
  
  .navbar {
    @colors: #theme.dark.navbar.colors(darks);
    background: @colors[primary];
    border: 1px solid @colors[secondary];
  }